Regression when parsing pytz (>=2011k) after 21.3 to 22.0 upgrade

[alexey-medvedchikov]

Hi,

Thank you for all your hard work!

At some point we upgraded packaging from v21.3 to v22.0 and found a regression.

v21.3 works fine:

# pip3.7 install packaging==21.3
...
# echo "pytz (>=2011k)" | python3.7 -c "import packaging; from packaging.requirements import Requirement; print(vars(Requirement(input())))"
{'name': 'pytz', 'url': None, 'extras': set(), 'specifier': <SpecifierSet('>=2011k')>, 'marker': None}

v23.0 and v22.0 are broken (last version that works is v21.3):

# pip3.7 install packaging==23.0
...

# echo "pytz (>=2011k)" | python3.7 -c "import packaging; from packaging.requirements import Requirement; print(vars(Requirement(input())))"
Traceback (most recent call last):
  File "/usr/local/lib/python3.7/site-packages/packaging/requirements.py", line 35, in __init__
    parsed = parse_requirement(requirement_string)
  File "/usr/local/lib/python3.7/site-packages/packaging/_parser.py", line 64, in parse_requirement
    return _parse_requirement(Tokenizer(source, rules=DEFAULT_RULES))
  File "/usr/local/lib/python3.7/site-packages/packaging/_parser.py", line 82, in _parse_requirement
    url, specifier, marker = _parse_requirement_details(tokenizer)
  File "/usr/local/lib/python3.7/site-packages/packaging/_parser.py", line 120, in _parse_requirement_details
    specifier = _parse_specifier(tokenizer)
  File "/usr/local/lib/python3.7/site-packages/packaging/_parser.py", line 209, in _parse_specifier
    tokenizer.consume("WS")
  File "/usr/local/lib/python3.7/contextlib.py", line 119, in __exit__
    next(self.gen)
  File "/usr/local/lib/python3.7/site-packages/packaging/_tokenizer.py", line 185, in enclosing_tokens
    span_start=open_position,
  File "/usr/local/lib/python3.7/site-packages/packaging/_tokenizer.py", line 166, in raise_syntax_error
    span=span,
packaging._tokenizer.ParserSyntaxError: Expected closing RIGHT_PARENTHESIS
    pytz (>=2011k)
         ~~~~~~~^

Test to reproduce the issue:

def test_specifier_ends_with_letter(self) -> None:
    # GIVEN
    to_parse = "name (>=2011k)"

    # WHEN
    req = Requirement(to_parse)

    # THEN
    assert req.name == "name"
    assert req.specifier == SpecifierSet('>=2011k')

Output from the test on current main:

self = <[AttributeError("'Requirement' object has no attribute 'name'") raised in repr()] Requirement object at 0x7fc3a1427040>
requirement_string = 'name (>=2011k)'

    def __init__(self, requirement_string: str) -> None:
        try:
            parsed = parse_requirement(requirement_string)
        except ParserSyntaxError as e:
>           raise InvalidRequirement(str(e)) from e
E           packaging.requirements.InvalidRequirement: Expected closing RIGHT_PARENTHESIS
E               name (>=2011k)
E                    ~~~~~~~^

[brettcannon]

This is expected as 2100k is not a valid version number (see https://packaging.python.org/en/latest/specifications/version-specifiers/ for the spec). Starting in packaging 22 we stopped being permissive about this, hence the change in semantics (we raised a warning to try and let users know ahead of time that this change was coming).

[pradyunsg]

See #530

[alexey-medvedchikov]

Thanks @brettcannon for the info. This is sad. 😞